This invention relates to an exhaust gas control means for a motorcycle and the like and more particularly to an improved arrangement for controlling the exhaust gases of an internal combustion engine and for arranging the exhaust components in a motorcycle.
It is well known that the tuning of an exhaust system for an internal combustion engine is particularly important in determining the performance of the engine. It has been found that the performance of the engine can be improved significantly if the exhaust pipe which conveys the exhaust gases from the engine exhaust port terminates within an expansion chamber. Although such an arrangement can increase the output of an engine at high speeds, such combined exhaust pipe and expansion chamber systems can offer certain disadvantage under other running conditions. This is particularly true when multiple exhaust pipes from different cylinders discharge into the same expansion chamber.
It has been found that resonant pulses will occur in the exhaust pipes which may be transmitted from one exhaust pipe back into another which can adversely affect the performance at mid-range. In order to obviate these difficulties, it has been proposed to provide a reflective control valve at the termination of the exhaust pipe which control valve is positioned in response to engine running characteristics. The exhaust control valve can create reflective pulses that will overcome the deleterious effects aforenoted. The copending applications "High Performance Exhaust System For Internal Combustion Engine", Ser. Nos. 935,340 and 934,342, filed Nov. 26, 1986 in the name of Hideaki Ueda and assigned to the assignee of this application, disclose arrangements wherein this principle is disclosed and the disclosure of these applications is incorporated herein by reference.
Although the arrangements disclosed in the aforenoted copending applications will overcome the performance difficulties discussed above, further improvement is possible. Specifically, the arrangements shown in the aforenoted copending applications position the control valves at the point where the exhaust pipes enter the expansion chamber. Although such an arrangement has utility in connection with certain engines and applications, the tuning of the lenght of the exhaust pipe and its relationship to the expansion chamber can be particularly important. In some instance, it is desirable to have the exhaust pipe extend into the expansion chamber and terminate within the expansion chamber.
Furthermore, with many types of compact vehicles such as motorcycles and the like, the actual placement of the valve in relation to the engine, bearing in mind that the exhaust system passes beneath the engine and ground clearance is extremely critical, can make arrangements of the type shown in the aforenoted copending applications less than fully satisfactory.
It is, therefore, a principal object of this invention to provide an improved exhaust control system for an internal combustion engine.
It is a further object of this invention to provide an improved exhaust gas control arrangement that is particularly adapted for exhaust gas tuning and which can be applied to compact vehicles such as motorcycles.
It is yet another object of this invention to provide an improved exhaust gas control arrangement for motorcycles.
In connection with the use of control valves in engine exhaust systems, the heat of the exhaust gases can have serious effects on the operation of the control valve. That is, the substantial temperature differences that can exist in an exhaust system from start up to normal running temperatures can be significant and the operation of the control valve could be adversely affected by such an arrangement.
It is, therefore, a still further object of this invention to provide an improved exhaust gas control arrangement for internal combustion engines wherein the exhaust control valve is maintained at a more uniform temperature.